Optic Nerve Hypoplasia

Ingrid Bockelmann

Optic Nerve Hypoplasia

(hypoplastic optic nerve)

Optic nerve hypoplasia is a congenital abnormality in which the optic disc (the end of the optic nerve which connects the retina to the brain) is smaller than normal and poorly developed.

Parts of the Visual System Affected

Optic nerve is underdeveloped.

One or both eyes can be affected, but is more commonly both eyes.

Effects of Optic Nerve Hypoplasia on the Visual System

Reduced visual acuity – inability to distinguish object details and shape, ranging from normal vision to vision which is severely impaired (no light perception)

If only a small number of nerve fibers failed to grow and the optic nerve is almost normal, the child will have normal vision.

If both optic nerves failed to grow properly, the child will have reduced sharpness of vision and may only see bright lights and large shapes.

If part of the optic nerve grew correctly, the child will have a partial vision loss, such as a depressed visual field (peripheral vision loss) and the remaining vision will be normal.

Nystagmus – roving, involuntary eye movement, can develop.

Squint can develop.

Loss of depth perception may be more severe if vision loss is great.

Mild photophobia – light sensitivity, may occur.

Common Treatments

If one eye is affected more than the other, eye patching can help improve vision by patching the child’s better eye to encourage the other eye to develop.

Wearing glasses can improve vision.

Condition is occasionally associated with hormonal deficits which can be recognized and treated by a pediatric endocrinologist.

Anticipated Functional Implications of Optic Nerve Hypoplasia

Due to reduced visual acuity, need assistance in interacting with the environment and with other people in order to learn.

Evaluation by an instructor of Orientation and Mobility is essential in meeting the child's needs, due to loss of both detail vision and visional field.

Need for increased print size for reading and school work.

Assistance in recognizing smaller objects.

Assistance in recognizing the facial expressions of others in order to respond appropriately.

References

http://www.aapos.org/displaycommon.cfm?an=1&subarticlenbr=87

Bishop, V.E. (1996). Preschool children with visual impairments. Retrieved July 1, 2009, from

http://www.tsbvi.edu/Education/preschool.htm

http://www.blindbabies.org/factsheet_onh.htm

Cassin, B., & Rubin, M.L. (Ed.). (2006). Dictionary of eye terminology (5th ed.). Gainesville, FL: Triad.

Corn, A.L., & Koenig, A.J. (Eds.). (1996). Foundations of low vision: Clinical and functional perspectives. New Yok: AFB Press.

Handbook of Ocular Disease Management. (2008). Optic nerve head hypoplasia. Retrieved July 1, 2009, from

http://www.revoptom.com/handbook/sect6i.htm

http://www.magicfoundation.org/www/docs/101.116/optic_nerve_hypoplasia_septo_optic_dysplasia.html

http://www.viscotland.org.uk/eyeconds/opticnerve.html